Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']

c, e, f, m, o